Diagnostic device for current sensor

Abstract

A diagnostic device for a current sensor disclosed herein may include an AC power calculation unit, a DC power calculation unit, and a determination unit. The AC power calculation unit may be configured to calculate AC power outputted from the inverter based on a measurement value measured by the current sensor. The DC power calculation unit may be configured to calculate DC power outputted from a DC power source that supplies power to the inverter. The determination unit may be configured to output a signal for notifying occurrence of an abnormality of the current sensor in a case where a difference between the calculated AC power and the calculated DC power is larger than a predetermined threshold.

What is claimed is: 
     
       1. A diagnostic device for a current sensor for measuring current flowing between an inverter and an AC motor, the diagnostic device comprising:
 an AC power calculation unit configured to calculate AC power outputted from the inverter based on a measurement value measured by the current sensor; 
 a DC power calculation unit configured to calculate DC power outputted from a DC power source that supplies power to the inverter; and 
 a determination unit configured to output a signal for notifying an abnormality of the current sensor in a case where a difference between the calculated AC power and the calculated DC power is larger than a predetermined threshold. 
 
     
     
       2. The diagnostic device of  claim 1 , wherein
 the AC motor is a three-phase AC motor, 
 the current sensor is provided for each of three phases of power cables that transmit three-phase AC from the inverter to the AC motor, 
 the diagnostic device is configured not to start a diagnosis while all of the three current sensors are operating normally and configured to start the diagnosis when an abnormality occurs in one of the current sensors, and 
 the AC power calculation unit is configured to calculate the AC power based on measurement values measured by two of the current sensors that operate normally when the AC motor is controlled based on the measurement values measured by the two of the current sensors that operate normally. 
 
     
     
       3. The diagnostic device of  claim 1 , wherein
 the predetermined threshold is set to a value larger than a power consumption of a specific device to which power is supplied from the DC power source. 
 
     
     
       4. The diagnostic device of  claim 1 , wherein
 the determination unit is configured to output the signal for notifying the abnormality of the current sensor in a case where the difference between the calculated AC power and the calculated DC power remains larger than the predetermined threshold over a predetermined time or longer.